So I have been doing some more research on Artorias' story and I ended up finding a few different websites that had pretty legit information about him. What I found was that when Artorias was 8 years old, his mother and father were killed by Lord Gwyn and Artorias was raised by his grandmother. Artorias from then on never truly got to know how his parents had died. He vowed to never suffer the same fate as his parents had. When Artorias turned 18, he started to take up the profession of sword fighting. Artorias entered into championships and started to defeat every competitor that came his way. Soon he had become the Grand Champion. Artorias grew up living by a code that his father had taught him, it went "The power of ignorance can only be defeated by knowledge and knowledge is power. But only the true champions of gods are the ones who do what they think is right." He adopted this code to help him remember his parents. At the age of 21, Artorias' grandmother had been killed by a fatal attack by a drake (Drakes are an imitator of the dragons).
Artorias knew that he must do something about his grandmother's death, so he created his own armor and he had a greatsword made for him by the Giant Blacksmith in Anor Londo. Artorias went to one of his most trusted friends and he asked them to make him a magic shield capable of blocking a dragon's fire breath. When Artorias gathered all his things and he set out on a quest to find the drake that murdered his grandmother. Artorias ventured into the Valley of Drakes and what he found were a whole family of drakes. One by one, he had killed them all. Only by his great strength and his bravery, he was able to defeat the drakes and had cast the remaining Elder Drake into the Abyss.
Artorias past the Valley of Drakes and went into the Dark Root Basin and found a wolf that had been wounded and was being attacked by Humanity Phantoms. The Phantoms were easily dispatched by Artorias. The injured wolf later known as Sif followed Artorias out of Dark Root Basin and accompanied him on his quest. Artorias found himself along with Sif in Anor Londo, where he found Dragonslayer Ornstein. Ornstein talked to Artorias and asked him to become one of the Knights of Gwyn. Artorias gladly accepted the offer and Orntstein gave him his ring which granted Artorias the power to have an unbendable will of steel. Later, Artorias was called into Lord Gwyn's chamber and Lord Gwyn asked Artorias to go into the New Londo Ruins and cast the Four Kings into the Abyss and seal up New Londo Ruins. Artorias told Gwyn that he will make sure that this task is done. Artorias went into New Londo Ruins and found Dark wraiths that shouldn't have been there since the only that they could get there is if Darkwraith Kaathe had brought them there. Artorias fought the darkwraiths and fell into the abyss where he fought the Four Kings and casted them into the darkness of the abyss. Darkwraith Kaathe appeared out of thin air and made a mysterious covenant with Artorias. Which later earned Artorias the name The Abysswalker.